text: The following equation can be used to correct a measured pollutant concentration in a dry emitted gas with a measured O content to an equivalent pollutant concentration in a dry emitted gas with a specified reference amount of O:
  As an example, a measured  concentration of 45 ppmv in a dry gas having 5 volume % O is:
  :45 × ( 20.9 - 3 ) ÷ ( 20.9 - 5 ) = 50.7 ppmv of 
  when corrected to a dry gas having a specified reference O content of 3 volume %.
  Note:
  * The measured gas concentration C must first be corrected to a dry basis before using the above equation.